1. Technical Field
The present invention relates to a sputtering device, and in particular to a sputtering device provided with a means for introducing magnetic field which is horizontal to a target surface to be processed by sputtering, so as to enable to perform uniform sputtering all over the surface of the target.
2. Background Art
Recently, as chip sizes of DRAM, MPU etc. become larger, silicon substrates used as their base bodies tend to have larger diameters. For the case that a thin film is to be formed on a larger-diameter base body by sputtering, it is desired to develop a sputtering device which can use a target having a larger diameter corresponding to a size of a base body, and can form a homogeneous deposit film having uniform film thickness on the base body.
As a conventional sputtering device, is mentioned an RF sputtering device FIG. 6) which has parallel plate electrodes and sputters a target while applying RF bias to the target, or a magnetron sputtering device (FIG. 7) which has such structure that magnetic field is generated from a back surface of a target, and which applies RF bias to the target while applying that magnetic field, so as to generate higher-density plasma on the surface of the target.
FIG. 9 shows a result of investigating sputtering capacity of the above-described RF sputtering device and magnetron sputtering device. Namely, after application of radio frequency power (13.56 MHz) to an Al target (150 mm.phi.) for 100 hours, scraped amounts of the target were investigated at 8 points on a surface of the target at intervals of 20 mm in the diametral direction to obtain the result. From this result, it is seen that a magnetron sputtering device has higher sputtering capacity than a RF sputtering device. As shown in FIG. 8, however, in the magnetron sputtering device, directions of the magnetic field generated on the target surface are not uniform, and accordingly, on the target surface, strong plasma is generated only in a limited space enclosed by magnetic flux.
One method of avoiding this problem that is known in the art utilizes a yoke structure design rotating a magnet mechanism on a back surface of a target, and the like. However, in the case that yoke structure design is employed, it leads to complication of the hardware, and in the case that the magnet mechanism is rotated, plasma is rotated and accordingly film substance grown on a substrate becomes weak in stress resistance. In addition, deposit film with uniform quality can not necessarily be obtained on a base body.